A device for the assembly of a motor vehicle clutch is already known, for example, from DE 299 15 947, which is provided with a pretensioning means. This pretensioning means has a base plate, which can be fastened to the clutch cover of the clutch. For fastening, three hook elements or draw hooks are provided on the base plate, which are mounted displaceably in longitudinal slots. These longitudinal slots are arranged in the base plate approximately in a triangular pattern and end a short distance in front of a through thread arranged centrally in the pressure plate. A pressing screw, which has a thrust collar toward the motor vehicle clutch in the assembled state, is screwed into this thread. The pressing screw is used, together with its thrust collar in the assembled state, i.e., in the state in which it is hung into the clutch cover with its draw hook, to pretension the plate spring arranged in the clutch cover. During normal operation, this plate spring is used to press the pressure plate, which is arranged in the clutch cover adjustably in relation thereto, against a carrier plate in order to bring about the torque closure of the clutch.
Such motor vehicle clutches are mounted stationarily on a driven plate during operation with their clutch cover, so that the carrier plate is clamped between the pressure plate and an annular friction lining of the driven plate by the pretensioning force of the plate spring when the clutch is not actuated. To make it possible to align the carrier plate concentrically with the pressure plate and consequently with the driven plate during assembly, it is proposed in the prior-art device that the pressing screw be provided with a central through hole, in which a centering tool can be arranged for the centered preassembly of the carrier plate on the pressure plate. The carrier plate can be attached to this centering tool, which passes through the through hole, and it can be fixed stationarily on the centering tool by a clamping device. When the carrier plate is attached to the centering tool, the clutch is pretensioned by means of the pretensioning means. The pretensioning means is now attached to the driven plate together with the clutch cover, the pressure plate arranged in the clutch cover together with the plate spring, as well as the carrier plate held on the pressure plate via the centering tool. The centering tool has a centering pin, which axially projects over the carrier plate and with which the centering tool can be placed concentrically, together with the complete clutch, on the driven plate arranged concentrically with the bearing bore of the crankshaft.
To actuate the pretensioning means, a transversely extending actuating lever, which transversely projects over the pressing screw on both sides, is arranged at the outer end of the central pressing screw. After the clutch has been attached to the driven plate and the clutch cover has been screwed to the driven plate by means of the mounting bolts, the pretensioning means is again released, so that the carrier plate is held clampingly in its desired centered position between the pressure plate and the driven plate. The gear can then be mounted and inserted with its gear shaft into the central clutch teeth of the centered carrier plate without problems.
To mount the carrier plate in a centered manner, the clamping device of the centering tool is designed as a centering cone, whose diameter or radial outside dimensions can be changed, so that it can be expanded and is held clampingly in the clutch teeth of the carrier plate. The carrier disk, which is held clampingly at the centering cone, can now be pulled against the pressure plate by a tension bolt, which is arranged on a corresponding draw spindle.
The drawback of this construction is that the clutch cover is to be aligned concentrically via its draw hook at the pretensioning means before the plate spring is pretensioned by the pressing screw. However, since the draw hooks are arranged in adjusting slots and have a considerable clearance in both the circumferential direction and the radial direction, such a concentric alignment of the clutch cover in relation to the pressing screw arranged concentrically in the base plate of the pretensioning means is not possible with sufficient accuracy. This in turn has the drawback that the clutch cover must be adjusted in the state in which it is attached to the driven plate, because when the clutch cover is mounted eccentrically in relation to the pressing screw, the clutch cover is also arranged eccentrically in relation to the centering tool and consequently also eccentrically in relation to the carrier plate when the centering tool is arranged in the through hole of the pressing screw. However, the clutch cover is also arranged eccentrically in relation to the driven plate in the state in which it is attached to the driven plate via the centering tool, so that an adjustment is indispensable, but this is possible only conditionally if at all because of the strong clamping forces of the pretensioning means.